In women, the effects of androgen deficiency have not been well studied, but likely include decrease in quality of life, poor libido, altered body composition and osteopenia. In a recent double-blind, placebo-control study treating oopherectomized women with transdermal testosterone, higher doses of testosterone supplementation resulted in an improvement in sexual function and psychological well-being. Little side effects were noted. Since both the adrenals and the ovaries contribute to testosterone product in normal women, patients with hypopituitarism are likely to have severely diminished androgen production from both sources. In fact, a recent study demonstrated very low levels of total and free testosterone as well as the androgen precursors, DHEAS, DHEA, and androstenedione in women with hypopituitarism. Although women with hypopituitarism often have decreased libido, altered body composition and impaired quality of life, symptoms possibly related to androgen deficiency, the effects of testosterone replacement in these women have not been studied. In the current proposal, we will test the hypothesis that female patients with hypopituitarism will benefit from physiological testosterone replacement in terms of objective and subjective sexual function, cognitive function, muscle size and physical performance and body composition. Female patients (ages 18 to 50 years) with testosterone deficiency secondary to hypopimitarism will receive either placebo or transdermal testosterone gel (2 mg of testosterone/day, leading to a targeted serum testosterone in the upper range of normal) in a double-blind study of 4 month duration. Potential side effects will be monitored. We expect this study will accurately assess the benefits and deleterious effects of physiological testosterone replacement in women with hypopituitarism. At the conclusion of this study, we expect to determine if testosterone will be added to the standard hormonal replacement for women with hypopituitarism.